Most editorial cartoons make a forceful point in a playful manner.  I think the artful combination of wit and cheeky criticism explains their popular appeal and potential effectiveness, but also hints at a possible limitation.  Historical studies of political cartoons (see Backer, 1996 and Neiman Reports, 2004) describe the ways in which Martin Luther in the 16th century, Benjamin Franklin in the 18th century, and people like Thomas Nast and Herb Block in the 19th and 20th centuries, respectively, satirized the political economies of their day through illustration.